This invention pertains to a mobile combine of the axial flow type in which, in the preferred construction, a pair of threshing compartments extend longitudinally within said combine, in side-by-side relationship, said threshing compartments comprising rotors having rasp bars thereon which coact with concaves which are complementary to the lower half of the paths described by the said rasp bars when rotating to effect threshing of crop material therebetween. The threshed and partially threshed crop material passes through grid-like openings in the concave and fall onto a grain pan which is transversely co-extensive with the chamber immediately below the concaves, said grain pan extending from the inlet end of the threshing compartments toward the other end thereof for at least part of the length of said threshing compartments.
In particular, the present invention pertains to a combine of the type referred to above in which the grain pan is mounted for fore-and-aft reciprocation longitudinally of the axis of the combine and discharges crop material from the rearward end of the grain pan onto similarly reciprocating sieve means which operates to separate desired crop material from chaff and other similar waste material. A typical combine of the type to which the present invention pertains is illustrated in prior U.S. Pat. No. 3,626,472, in the name of Edward William Rowland-Hill, dated Dec. 7, 1971. In said patent, the grain pan and sieve mechanism are mounted for longitudinal, fore-and-aft reciprocation.
It has been found in operation of a combine of this type on hillsides, there is a distinct tendency for uneven distribution of threshed crop material upon the grain pan, such as a greater quantity thereof accumulating on the downhill side of the grain pan, which results in less efficiency due to loss of capacity and grain loss. In addition, combines of this type normally employ a principal or main concave immediately below each rotor and a concave extension which extends radially farther around the path described by the rasp bars of the rotor respectively toward opposite sides of the interior compartment of the combine in which the threshing compartments are located. Due to the fact that the rotors of the threshing compartments respectively rotate in opposite rotary direction and, as viewed from the forward end of the combine, the left hand rotor rotates clockwise and the right hand rotor rotates counterclockwise, said rotors respectively tend to carry the crop material up the outer side portions of the threshing compartments and discharge the grain through said concave extensions, which results in a heavier accumulation of grain occurring respectively along the outer sides of the grain pan than centrally thereof.
In view of the foregoing, the present invention has been devised to provide a more even distribution of grain upon the grain pan, regardless of whether the combine is operating on substantially level terrain, or on a hillside, and this is accomplished by mechanism described in detail below.